Category: Linux

Atlassian JIRA Internal Server Error
On on Jira Server, when accessing the site get following error

JIRA — Internal Server Error
Error reference: b64e4876-0fc1-439a-a46d-4a3255a48230

Unable to render full error details at this time. Please consult the error logs for more information.

The problem was disk full.

root@jira /var/atlassian/application-data/jira # du -h –max-depth=1
1.1M ./analytics-logs
4.0G ./plugins
293M ./log
72K ./structure
32M ./tmp
11M ./caches
632K ./logs
52K ./tempo
32G ./export
368M ./data
96K ./import
352K ./monitor
4.0K ./logos
8.5M ./bt-templates
37G .
root@jira /var/atlassian/application-data/jira #

The folder /var/atlassian/application-data/jira/export used 32 GB disk space. This folder store daily backups.

I removed some of the older backups last last year, restarted the server, that fixed the problem.

To avoid this happening again, set a cronjob
```
vi /usr/serverok/clean.sh
```
Add
```
#!/bin/bash

/bin/find /var/atlassian/application-data/jira/export/ -type f -mtime +60 -name "*.zip" -delete
```
This will delete files older than 60 days.

Set it to run daily with crontab -e
```
@daily  /usr/serverok/clean.sh > /dev/null 2>&1
```
May 15, 2018

Enable Error Logging in php-fpm

Edit your pool file

vi /etc/php/7.0/fpm/pool.d/www.conf

Add

catch_workers_output = yes
php_flag[display_errors] = on
php_admin_value[error_log] = /var/log/fpm-php.www.log
php_admin_flag[log_errors] = on

if you only enable “log_errors”, then errors go to default nginx error log.

php-fpm

May 12, 2018

mount
Remount a file system in rw mode
```
mount -o remount,rw /
```
May 3, 2018

Mount Windows Share in Linux

On Ubuntu, install cifs-utils

apt-get install cifs-utils

First create a directory on which we can mount the windows share

mkdir /media/SHARE_NAME

Now create a file to store windows share username and password.

vi /etc/SHARE_NAME.smbcredentials

Add following to the file

username=YOUR_WINDOWS_SHARE_USER
password=YOUR_WINDOWS_SHARE_PASSWORD

Now run

mount -t cifs //192.168.0.4/SHARE_NAME /media/SHARE_NAME -o credentials=/etc/SHARE_NAME.smbcredentials,uid=LINUX_USER_NAME,iocharset=utf8,sec=ntlm,rw,dir_mode=0777,file_mode=0666

192.168.0.4 – Replace with IP of your Windows computer with share.

LINUX_USER_NAME – Replace with the Linux user name you want the files to be owned.

To make share mounted on boot, edit

vi /etc/fstab

Add

//192.168.0.4/SHARE_NAME  /media/SHARE_NAME  cifs  credentials=/etc/SHARE_NAME.smbcredentials,uid=LINUX_USER_NAME,gid=GID_OF_LINUX_USER,_netdev,iocharset=utf8,dir_mode=0777,file_mode=0666  0  0

mount

May 3, 2018

Debian 9 OVH Bridge Network Configuration

When you run VPS on OVH network behind bridge network, you need to create VMAC for each IP and assign to your network card.

Once this is done, you need to use following network configuration in your /etc/network/inferfaces file.

auto lo ens18
iface lo inet loopback
auto ens18
iface ens18 inet static
    address FAILOVER_IP
    netmask 255.255.255.255
    broadcast FAILOVER_IP
    post-up ip route add GATEWAY_IP dev ens18
    post-up ip route add default via GATEWAY_IP dev ens18
    pre-down ip route del GATEWAY_IP dev ens18
    pre-down ip route del default via GATEWAY_IP dev ens18

FAILOVER_IP = the IP you will be using for the virual machine.

GATEWAY_IP = IP of the Host server with last digits replaced by 254. If your servers main IP is XX.YY.ZZ.100, then Your GATEWAY_IP is XX.YY.ZZ.254

Here is an example config file i use in one of my VPS

auto ens18
iface ens18 inet static
    address 198.50.234.186
    netmask 255.255.255.255
    broadcast 198.50.234.186
    dns-nameservers 8.8.8.8 8.8.4.4
    post-up ip route add 158.69.124.254 dev ens18
    post-up ip route add default via 158.69.124.254 dev ens18
    pre-down ip route delete 158.69.124.254 dev ens18
    pre-down ip route delete default via 158.69.124.254 dev ens18

I made a pull request to OVH as OVH documentation use route command, that is deprecated in Debian 9 and Ubuntu 18.04. We need to use “ip route” command instead of “route” command.

April 30, 2018

Resize gcow2 image with qemu

To resize gcow2 image, run

qemu-img resize FILE.qcow2 +10GB

To create a gcow2 image, run

qemu-img create -f qcow2 -o preallocation=metadata FILE.new 10G

You can also use

virt-resize --debug  --expand /dev/vda1 FILE.qcow2 FILE.qcow2.new

virt-resize is part of http://libguestfs.org

April 30, 2018

500 I won’t open a connection to x.x.x.x (only to y.y.y.y)
When connecting to FTP server from a remote server hosted in Microsoft Azure i get error

500 I won’t open a connection to x.x.x.x (only to y.y.y.y)

This is because you are behind NAT firewall and trying to use FTP in Active mode.

To fix the error, enable FTP passive mode with command
```
passive
```
ftp
April 29, 2018
tar
To extract a tar file, run
```
tar xf file.tar.gz
```
Uncompress tar.gz file
```
tar -zxvf ncftp-3.2.2-src.tar.gz
```
Uncompress tar.bz2 file
```
tar -jxvf ncftp-3.2.2-src.tar.bz2
```
Create a tar file
```
tar -cvf file.tar FOLDER_OR_FILE_NAME
```
Example
```
tar -cvf backup.tar public_html
```
Once backup.tar file is created, you can make it tar.gz with command
```
gzip backup.tar
```
Exclude a folder from tar file

To exclude a folder, you can use –exclude option.
```
tar cvf backup.tar --exclude=public_html/uploads --exclude=public_html/wordpress public_html
```
List content of a tar file
```
tar --list --verbose --file=BACKUP.tar.gz
```
If you want to exclude a folder from the file list, use
```
tar --list --verbose --file=BACKUP.tar.gz --exclude=home/haridy/Maildir
```
This will exclude all files that are inside folder “home/haridy/Maildir”. You can use multiple –exclude if required.

Using tar over SSH Session
Split Large file into smaller files
How to view the contents of tar.gz file
April 29, 2018
Debian
When I install Debian 9 from CD, it did install with /etc/apt/sources.list pointing to CD.

To get this work properly, you need to edit the file
```
vi /etc/apt/sources.list
```
Replace content with
```
deb http://security.debian.org/ stretch/updates main
deb-src http://security.debian.org/ stretch/updates main
deb http://ftp.debian.org/debian/ stretch-updates main
deb-src http://ftp.debian.org/debian/ stretch-updates main
deb http://ftp.us.debian.org/debian stable main contrib non-free
```
Debian Upgrade
- How to upgrade Debian 9 to Debian 10
- How to Upgrade Debian 10 to Debian 11
April 29, 2018
Unable to detect ICU prefix
When compiling PHP, i get following error.

checking whether to enable internationalization support… yes
checking for icu-config… no
checking for location of ICU headers and libraries… not found
configure: error: Unable to detect ICU prefix or no failed. Please verify ICU install prefix and make sure icu-config works.

To fix, install libicu dev package.

On CentOS/RHEL
```
yum -y install libicu-devel
```
On Debian/Ubuntu
```
apt -y install libicu-dev
```
Errors
April 28, 2018

Datacenter

Here is some info for checking speed for various data centers.

OVH Sydney, Australia

Test IPv4 : 139.99.130.17
Test IPv6 : 2402:1f00:8100:211::1
Test files : http://syd.infrastructures.ovh/
Test latency : http://syd.smokeping.ovh.net/smokeping?target=APAC
Looking Glass: https://lg.ovh.net
Network status: http://weathermap.ovh.net/#apac

OVH, Singapore

Test IPv4 : 139.99.8.97
Test IPv6 : 2402:1f00:8000:261::1
Test files : http://sgp.infrastructures.ovh/
Test latency : http://sgp.smokeping.ovh.net/smokeping?target=APAC
Looking Glass: https://lg.ovh.net
Network status: http://weathermap.ovh.net/#apac

Dedicated

April 25, 2018

Install MySQL 8 on CentOS, RHEL 6/7
To Add MySQL yum repository to your server, go to

https://dev.mysql.com/downloads/repo/yum/

Download the rpm file available.

For RHEL/CentOS 7
```
wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
rpm -ivh mysql80-community-release-el7-3.noarch.rpm
```
For RHEL/CentOS 6
```
wget https://dev.mysql.com/get/mysql80-community-release-el6-1.noarch.rpm
rpm -ivh mysql80-community-release-el6-1.noarch.rpm
```
Installing MySQL Server
```
yum install mysql-community-server
```
Stop/Start MySQL

To stop/start MySQL, use service name “mysqld”.
```
systemctl start mysqld
systemctl stop mysqld
systemctl restart mysqld
```
MySQL 8 root Password

When MySQL first starts, it create a random password and store in MySQL log file. To find the MySQL root password, run
```
grep 'temporary password' /var/log/mysqld.log
```
This default password don’t allow you to do anything, so login to MySQL with this password and set a secure password for root.
```
ALTER USER 'root'@'localhost' IDENTIFIED  BY 'MYSQL_ROOT_PASSOWRD';
```
MYSQL_ROOT_PASSOWRD – replace it with you secure new MySQL root password.

Installing Older Version of MySQL

When you add MySQL repository, it activate latest version by default. If you want older version, say 5.7, you need to activate it.

To see available repository, run
```
yum repolist all | grep mysql
```
To disable MySQL 8 repository, run
```
yum-config-manager --disable mysql80-community
```
To enable MySQL 5.7 repository, run
```
yum-config-manager --enable mysql57-community
```
Now installing MySQL server will install MySQL 5.7 instead of latest version.

MySQL CentOS
April 23, 2018

Category: Linux

Create a tar file

Exclude a folder from tar file

List content of a tar file

Debian Upgrade